1. Thou shalt not forget thy primary and original purpose of thy phone.
Texting is the last line of defense. Sort-of-boyfriends and girlfriends, ancillary friendships, and all sorts of other, crappy, destructive, hanging-on-by-a-thread relationships are now held together by texting (and perhaps, facebook super walls). If you're only texting and never calling, you're merely prolonging something that most likely should not continue. Which is totally fine as long as you know your place. Don't like getting relegated to "wanna hump?" Start using the original function instead of whining about it. Moving on.
3. Thou shalt not commit "sexting" (aka "sexy texting" aka "pet names and/or the electronic whispering of sweet nothings") unless thy intent is to follow up beyond virtual reality.
Yes it's easy to become invigorated at midnight when say, no girls in the bar will talk to you, but to text some poor chick that you're thinking about them, only to pretend said event never happened when say, your girlfriend gets back in town, is, as you are well aware, just a real d-bag maneuver. So quit doing it to my friends cause then I have to nurse them back to health because you're a jerk. This commandment could also be entitled, "Thou shall commit sincerity."
4. Thou shall back off.
Come on. Can you just back off for a second? Sometimes people get busy or all their updates are depressing and they really don't want to have to rehash them or they aren't the type of person that feels the need to talk to all people they know every single day (because some of the people they know are not that interesting). If you have texted three times in a row with no response, listen to the little voice telling you to stop. The rule of scarcity, people. Use it. Or heed the consequences of a quick fade (vs. aforementioned slow fade—see commandment before the previous) in which you find your overeager beaver has scared off someone much cooler than you.
Texting someone in front of someone else, multiple times, is kind of rude unless it's about that person coming to join you both. Don't act like you don't know this. If you must check more than a few texts, don't immediately hunch over and respond, consider instead showing the current party what the text is, if it's funny, unless it is about the possibility of you hooking up with current party. And if you are trying to hook up with current party, why are you checking your text about it anyway? Just do it! And send me a text about it later. With a lot of details, please. Maybe some pictures too.